Electrical Impedance Spectroscopy (EIS) measures the electrical impedance of a substance as a function of the frequency of an applied electrical current. An application of the EIS includes measuring the electrical impedance of biological tissues. Generally, a biological tissue exhibits electrical impedance that varies with frequency. The biological tissue contains components with both resistive and capacitive properties resulting in a complex electrical impedance. The magnitude and phase of the electrical impedance and the dependence of the electrical impedance on frequency are functions of the tissue's composition. Measuring the electrical impedance across a range of frequencies will generate a spectrum that is characteristic of the biological tissue. Changes in the impedance spectrum can be related to changes in the underlying nature of the biological tissue.
EIS measurements are relevant to many medical applications, such as plaque diagnostics in an artery or in other blood vessels. For example, EIS measurements can help diagnose Oxidized low-density lipoprotein (OxLDL) lesions on an intima of an artery. Generally, the accuracy of an EIS-based medical application depends on the accuracy of the EIS measurements. As such, accurately measuring the impedance of a biological tissue is of utmost importance in the EIS-based medical application.